Brake-pressure-testing machine



oct. 7, 1930. J, C, ZEDER 1,777,423

BRAKE PRESSURE TESTING MACHINE Filed Nov. 8. 1926 2 Sheets-Sheet l Oct. 7, 1930. J. c. ZEDER 1,777,423

BRAKE PRESSURE TESTING MACHINE Filed Nov. 8, 1926 2 Sheets-Sheet 2 [N VEA/.TOR f g W M156 c Z555# ya? l ATTORNEY Patented oct. 7; 1930 UNITED STATES a PATENT OFFICE JAMES C. ZEDER, OF DETROIT, MICHIGAN, ASSIGNOR TO CHRYSLER CORPORATION, OF DETROIT, MICHIGAN, A CORPORATION 0F DELAWARE l BRAXE-PRESSURE-TESTING MACHINE Application illed November 8, 1926. Serial No. 146,891.

It is the primar object of this invention to provide a machine for testing the quality and coefficient of friction of frictional surfaces or the relative coeiiicient of friction between different frictional surfaces.

' Considerable variances are found in the quality of lfrictional surfaces. Taking for example, brake linings, some may have a high coeticient of friction but poor wearing qualities, while others may have a low coeicient of friction and good wearing qualltles, neither of which are desirable for commercial ings on motor vehicles.

An important object of this invention is to test frictional surfaces for both wearing quality and coefficient of friction by sub] ecting the surfaces to the same conditions as exist when the surfaces are in use and accelerating the results of ordinary usage.

Another` object of the invention is to rotate a drum with the surface in frictional engagement therewith. Means have been provided for `varying and recording the amount of pressure exerted on the frictional surfaces and mea'ns for recording the amount of frictional grip has been provided, illustrated by recording` the pressure caused by limited angular movement of the supporting mechanism for a brake lining with the drum.

A further object is to cool the drum, illus-l trated by causing a circulation of water through the interior of the drum.-

Other objects and advantages will more fully appear from the following description taken in connection with the accompanying drawings in which lf'ig. 1 is an end view of the machine, parts being broken away and parts in section.

Fig. 2 is a sectional view on line 2 2 of Fig. 1.

big; 3 is a fragmentary view of the panel which supports the indicating instruments and controls.

Fig. 4 is a detail in section showing a means` for securing a lining to be tested to the shoe.

Referring to the illustrated embodiment of my invention, a rotatable shaft 10 is jourits naled in a bearing 12 at one end `and has use, particularly for use as brake band lin-v opposite end journaled in a bearing 14 carried by a rotatable support 16 which is journaled in the base 18 by the bearings 20. At

one end of the shaft 10, a driving connection V22 is secured adapted to be connected to a driving means, not shown. The opposite end of the shaft 10 is provided with a drum 24, rotatable therewith.

The support 1 6 is provided with-a sleeve portion 26 around the shaft 10 and is independently rotatable within the bearings 20. A brake shoe 28 is pivotally supported on a swinging dink 30. The latter is pivotally supported on a flange 32 of the support 16.

A piston 34 reciprocating in a cylinder 36, carried by the support 16, is connected to the link 30 by a rod 38 and movement of the piston 34 causes the shoe to be brought into frictional engagement4 with the drum 24 or` to be retracted therefrom. The piston isoperated by a fluid pressure in a line 40. The

pressure is obtained by means of a pump 42.

A valve 44, between the pump 42 and line 40, when closed, maintains a given pressure built up by the pump'. The pressure is recorded by a pressure .gauge 46 through a connection 48 to the line 40.

A section of a brake lining 50 is placed on the shoe 28. between the drum and shoe, and pins 52 securely hold the lining in position against slipping.

`It will be understood that by applying a pressure in the line 40 the lining 50 will be in frictional engagement with the rotating drum 24 and the friction will cause the shoe, its connections and the support 16 to tend to rotate with trie drum 24. An adjustable weight 53 has been provided to return the support to its normal position when the pressure in the line 40 isrelieved.

' An arm 54 carried by the housing 16 is connected to a piston 56 reciprocating in a cylinder 58 secured to the support 18. Another pressure line 60 is in communication with Y I closed shutting o engage said drum, fluid means for resisting the angular movement of a pressure in the cylinder 58 and line 60 to be built up and recorded on the gauge 62.

An adjustment has been provided for the cylinder 58 which comprises a pair of bolts 70 adapted to engage slots 72 in the base 18. The arm 54 is provided with apertures 74, one of which receives the pin 76 securing the connecting rod 78. Thus the effective length of the arms 54 may be varied.

The amount of frictional grip of the liningon the drum can be measured in pounds by the above described arrangement and in comparing one lining with another, a constant pressure is maintained on the shoe 28 and the difference in frictional grip is determined by .the difference in pressures recorded on the .gauge 62. When different linings are run each for an equal given length of time the gauge 46. This difference in pressures is due to the wearin away of one lining more than the other, which consequently causes a dro in the pressure.

To properly duplicate conditions Where the brake is exposed to moisture a pipe has been provided in the support 16 which supplies a stream of liquid to the drum and linlng. The supply is controlled by a valve 82 and if it is desired to test the lining or frictional grip on a dr, surface the valve may be the suppl of liquid.

A passage has been provide through which Water or any other cooling medium may pass to cool the drum. The passage com rises an inlet conduit 84 communicating Wit an annular chamber 86 in the support 18. A passage 88 in the shaft 10 conducts the liquid to f the interior of the drum 24 and a passage 90 returns the liquid from the drum to an annular chamber- 92 and out through a conduit 94. Suitable packing glands 96 are provided around the shaft l0.

While the above description has been directed to one specific embodiment of my invention, it is to be understood that various changes includin size and arrangement of parts may be mae without departing from the spirit thereof and it is not my intention to limit its sco e other than by the terms of the appended c aims.

What I claim is:

l. In a testing machine of the class described comprising, a rotatable drum, pressure controlled means adapted to frictionally pressure controlled said first named means with said drum, and means for indicating said pressures.

' 2. In a testing machine of theclass described comprising, a rotatable drum, a pressure controlled shoe having a lining adapted for frictional engagement with said drum, a rotatable support for said shoe co-axial with said drum, fluid pressure means for resisting the angular movement of `said supdifl'erence in pressuresl is recorded on the port, and means for indicating the amount of said fluid pressure.

3. In a testing machine of the class described com rising, a rotatable drum, a pressure control ed shoe having a lining adapted for frictional engagement with said drum, means for indicating the ressure on said shoe, a rotatable support or said shoe coaxial with said drum, fluid pressure means for resisting the angular movement of said support, and means for indicating the amount of resistance to movement of said support.

4. In a testing machine of the class described comprising, a rotatable drum, a rotatable support, coaxial with said drum, a shoe carried b said support and having a lining adapted gbr frictional engagement with said drum, a pressure controlled chamber carried by said support, a piston in said chamber operatively connected to said chamber, a stationary pressure chamber, a piston connected to said support reciprocating in said stationary pressure chamber, and means for indicating the pressure in said last named chamber caused by the angular movement of said Support and piston.

5. In a testing machine of the class described comprising, a rotatable drum, a shoe having a lining adapted for frictional engagement with said drum, a rotatable support for said shoe co-axial with said drum, fluid pressure means for resisting the angular movement of said support, means for indicating a pressure caused by the resistance of said support, and means for varying the proportion of said pressure indication to the resistance on said support.

' JAMES C. ZEDER.

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